Keyboards and computers for use in most German-speaking countries are made with the "Qwertz" keyboard layout. If you have such a keyboard, but wish to type according to the United States' "Qwerty" layout, you can easily change your keyboard's behaviour using your operating system's control panel.
If you're running Windows Vista, open the control panel and select "Change Keyboards or Other Input Methods" under "Clock, Language and Region." Click the "Change Keyboards" button. Click "Add" and check "English" > "Keyboard" > "US." Press "OK." Set the default language to "English (United States) - US," and remove the German/Qwertz keyboard layout. Other versions of Windows follow the same steps, except that the keyboard settings are found under "Regional and Language Options" in XP, and "Keyboard" in prior versions.
If you use Mac OS X, choose "System Preferences" from the dock, click the "International" icon, and choose "US" under the "Input Menu" tab. Uncheck "German" or whatever language you had selected previously if you do not wish to be able to switch between the two. For older Macs, you can follow the same steps after opening "Control Panels" under the Apple Menu and selecting "Keyboard."
If you're a Linux user, you have multiple ways to change keyboard layouts, depending on your desktop environment. A simple solution that will work for all XWindows users is to run the command "setxkbmap us" in a terminal.
Your keyboard will now function exactly like a Qwerty keyboard, even though the keys still have the Qwertz letters printed on them. You can place small stickers with the letters written or printed on them over the keys that are different between the two layouts. You can find a graphical layout of a Qwerty keyboard on Wikipedia, for reference (see Resources below).